Generic lighting control consoles serve for controlling lighting systems such as those employed in theaters or on concert stages, for instance. Routinely, said lighting systems comprise a plurality of lighting devices, for instance stage spotlights, wherein the lighting devices on their own in many cases can also be switched between a plurality of lighting states, for instance between different colors. These different lighting states are stored and controlled in the lighting program of the lighting control console by way of programmed parameters. Here, standard lighting systems may comprise up to several thousand lighting devices. In order to be able to control such complex lighting systems, the generic lighting control consoles are equipped with a digital processor, which permits digital data and signal processing. For storing the data, a digital memory is further provided, which in particular allows for archiving of lighting programs.
For programming the lighting program or for controlling the lighting program while it is running, operators have to enter control commands as input values. Said control commands can, for instance, be the selection of a specific lighting device or the setting of a specific parameter. For entering these control commands, mechanical control elements, for instance key buttons, rotary controls or slide controls, are available at known lighting control consoles. Here, the control commands being assigned to the individual control elements may be altered by way of suitable menu changeovers in order to be able to program and control correspondingly complex lighting programs.
Dual encoders are input apparatuses, which allow users to enter an assigned electrical signal by turning an actuating element. Here, dual encoders are characterized in that they do not only include one actuating element, for instance a rotary knob or a rotary disk, but two actuating elements. Here, both actuating elements are connected to a shaft being mounted so as to be rotatable. One rotation signal generator, which is able to directly or indirectly detect a turning of the shaft, is assigned to each shaft. In each instance, the two rotation signal generators then generate an electrical signal after having detected an adjusting movement at the shaft.
Besides, the two shafts are equipped with one locking mechanism in each instance, which mechanism is able to lock the shafts in different rotational positions. In this manner, the signals having been generated by the rotation signal generator can show a switchover between two locking positions by turning the shaft.
For instance, but by no means exclusively, known dual encoders may be used for entering two adjusting values at an appliance, for instance the X value and the Y value in a Cartesian coordinate system, with discrete rates in each instance, with only minor adjusting movements of the hand. From document DE 33 36 746 A1, a simple encoder is known, which is embodied in the manner of a rotary switch. Said encoder has a mechanical locking mechanism, which is able to fix the shaft in different locking positions. Said mechanical locking mechanism has the disadvantage that the mechanical connections of the locking mechanism are subject to relatively high wear, due to which the locking mechanism becomes sluggish or fails completely after a certain running time.